Transient absorption of copper selenide nanowires of different stoichiometry

G.Juška, V.Gulbinas, A.Jagminas

Abstract

Copper selenide nanowires of different stoichiometric compositions and having different density of defects that form intraband states embedded in a porous alumina layer have been investigated by means of a femtosecond absorption pump-probe technique. Depending on the formation conditions, different samples have different absorption spectra in the near-infrared spectral range, but all of them show bleaching of the most intense absorption bands, which competes with the induced absorption of free charge carriers. A transient absorption relaxation takes place in two steps, with time constants of about 1 ps and several tens of ps. Relative contribution of the fast relaxation component increases in samples with the higher density of defect states forming the recombination centres.